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Glossary

Agrobacterium tumefaciens
A common soil bacterium that causes crown gall disease by transferring some of its DNA to the plant host. Scientists alter Agrobacterium so that it no longer causes the disease but is still able to transfer DNA. They then use this altered Agrobacterium to ferry desirable genes into plants.
Amino acid
The fundamental building blocks of a protein molecule. A protein is composed of a chain of hundreds or thousands of amino acids. Our bodies can synthesize most of the amino acids. However, eight amino acids (called "essential amino acids") must be obtained from food.
Antibody
A protein produced in response to the presence of a specific antigen.
Antigen
A foreign substance that elicits the production of antibodies.
Anti-sense technology
The use of an RNA molecule to block gene expression by interfering with protein production. This technique is used commercially in tomatoes to slow ripening for better shipping and longer shelf life.
Assay
A method for determining the presence or quantity of a component.
Blymphocytes (B cells)
A type of cell that produces antibodies.
Bacillus thuringiensis
A naturally occurring bacterium with pesticidal properties. Bacillus thuringiensis produces a protein (Bt toxin) that is toxic only to certain insect larvae that consume it.
Bacteriophage
A virus that infects bacteria. Also called a phage.
Bioassay
A method of determining the effect of a compound by quantifying its effect on living organisms or their component parts.
Biocatalyst
An enzyme that activates or speeds up a chemical reaction.
Biological control
The use of one organism to control the population size of another organism.
Biological molecules
Large, complex molecules, such as proteins, nucleic acids, lipids and carbohydrates, that are produced only by living organisms. Biological molecules are often referred to as macromolecules or biopolymers.
Bioprocessing
A technique in which microorganisms, living cells, or their components are used to produce a desired end product.
Bioreactor
A container used for bioprocessing.
Bioremediation
The use of organisms, usually microorganisms, to break down pollutants in soil, air or groundwater.
Biosensor technology
The use of cells or biological molecules in an electronic system to detect specific substances. Consists of a biological sensing agent coupled with a microelectronic circuit.
Biosynthesis
Production of a chemical by a living organism.
Biotechnology
(Ancient definition:) The use of living organisms to solve problems and make useful products. (Modern definition:) A collection of technologies that use living cells and/or biological molecules to solve problems and make useful products.
Callus
A cluster of undifferentiated plant cells that have the capacity to regenerate a whole plant in some species.
Catalyst
A substance that speeds up a chemical reaction, but is not itself changed during the reaction.
Cell
The smallest structural unit of living organisms that is able to grow and reproduce independently.
Cell culture
A technique for growing cells under laboratory conditions.
Cell fusion
The formation of a hybrid cell produced by fusing two different cells.
Chromosome
Components in a cell that contain genetic information. Each chromosome contains numerous genes. Chromosomes occur in pairs: one obtained from the mother; the other from the father. Chromosomes of different pairs are often visibly different from each other (see also DNA).
Clone
A cell or collection of cells containing identical genetic material. Clones are produced from a single parent cell.
Culture
To grow living organisms in a prepared medium or media.
Culture medium
A nutrient system for artificially growing bacteria or other cells.
DNA (deoxyribonucleic acid)
The chemical molecule that is the basic genetic material found in all cells. DNA is inherited. Because DNA is a very long, thin molecule, it is packaged into units called chromosomes. DNA belongs to a class of biological molecules called nucleic acids.
DNA fingerprinting (or DNA typing)
A technique for identifying individual organisms based upon the uniqueness of their DNA pattern. The technique has applications in forensics, paternity testing, anthropology, conservation biology and ecological research.
DNA ligase
An enzyme that rejoins cut pieces of DNA.
DNA probe
A molecule that has been labeled with a radioactive isotope, dye or enzyme and is used to locate a particular portion of a DNA molecule.
DNA sequence
The order of nucleotide bases in the DNA molecule.
Double helix
A term used to describe the configuration of a DNA molecule. The helix consists of two spiraling strands of nucleotides held together with chemical bonds.
E. coli (Escherichia coli)
A bacterium commonly found in the intestinal tracts of most vertebrates. It is used extensively in recombinant DNA research because it has been genetically well characterized.
Enzyme
A protein that accelerates the rate of chemical reactions. Enzymes are catalysts that promote reactions repeatedly, without being damaged by the reactions.
Eukaryote
An organism whose genetic material is located within a nucleus. Yeast, fungi, protozoans, plants and animals are eukaryotes.
Expression
The physical manifestation of the information contained in a gene.
Fermentation
A process of growing microorganisms to produce various chemical or pharmaceutical compounds. Microbes are usually incubated under specific conditions in large tanks called fermenters. Fermentation is a specific type of bioprocessing.
Gene
A unit of hereditary information. A gene is a section of a DNA molecule that specifies the production of a particular protein.
Gene amplification
The increase, within a cell, of the number of copies of a given gene.
Gene mapping
Determining the relative locations of genes on a chromosome.
Genetic code
The way genetic information is stored in living organisms.
Genetic engineering
The technique of removing, modifying or adding genes to a DNA molecule in order to change the information it contains. By changing this information, genetic engineering changes the type or amount of proteins an organism is capable of producing.
Genome
The total hereditary material of a cell.
Genotype
The specific genetic makeup of an organism, as contrasted with the actual characteristics of an organism (see phenotype).
Hybridization
Production of offspring, or hybrids, from genetically dissimilar parents. In selective breeding, it usually refers to the offspring of two different species.
Hybridoma
A type of hybrid cell produced by fusing a normal cell with a tumor cell. When lymphocytes (antibody-producing cells) are fused to the tumor cells, the resulting hybridomas produce antibodies and maintain rapid, sustained growth, producing large amounts of an antibody. Hybridomas are the source of monoclonal antibodies.
Immunoassay
A technique for identifying substances, based on the use of antibodies.
Immunotoxin
The coupling of an antibody and a molecule that is toxic to the cell.
In vitro
Performed in a test tube or other laboratory apparatus.
In vitro selection
Selection at the cellular or callus stage of individuals possessing certain traits, such as herbicide resistance.
In vivo
In the living organism.
Interferon
A protein produced naturally by the cells of our bodies. It increases the resistance of surrounding cells to attacks by viruses. One type of interferon, alpha interferon, is effective against certain types of cancer. Others may prove effective in treating autoimmune diseases.
Interleukin
A protein produced naturally by our bodies to stimulate our immune systems. There are at least 18 known kinds of interleukins.
Leukocyte
A white blood cell, an important component of the body's immune system.
Lymphocyte
A type of leukocyte found in the blood, lymph nodes and certain organs. Lymphocytes are continuously made in the bone marrow (see also B lymphocytes and T lymphocytes).
Macrophage
A type of white blood cell that ingests dead tissue and cells and is involved in producing Interleukin 1.
Marker gene
Genes that identify which plants have been successfully transformed.
Molecular genetics
The study of the molecular structure and function of genes.
Monoclonal antibody
Highly specific, purified antibody that is derived from only one clone of cells and recognizes only one antigen.
Multigenic
Many genes are involved in the expression of a trait.
Mutagen
A substance that induces mutations.
Mutant
A cell microorganism that manifests new characteristics due to a change in its genetic material.
Mutation
A change in the genetic information.
Nucleic acid
A biological molecule composed of a long chain of nucleotides. DNA is made of thousands of four different nucleotides repeated randomly.
Nucleotide
A compound made up of these three components: a sugar, phosphate and a nitrogen-containing base. Found as individual molecules (e.g., ATP, the "energy molecule"), or as many nucleotides linked together in a chain (nucleic acid such as DNA).
Oncogene
A gene thought to be capable of producing cancer.
Oncology
The study of tumors.
Phenotype
The observable characteristics of an organism as opposed to the set of genes it possesses (its genotype).The phenotype that an organism manifests is a result of both genetic and environmental factors. Therefore, organisms with the same genotype may display different phenotypes due to environmental factors. Conversely, organisms with the same phenotypes may have different genotypes.
Plasmid
A small, circular piece of DNA found outside the chromosome in bacteria. Plasmids are the principal tools for inserting new genetic information into microorganisms or plants.
Polymerase chain reaction (PCR)
A technique for quickly making many copies of a specific segment of DNA.
Prokaryotes
Organisms whose genetic material is not enclosed by a nucleus. The most common examples are bacteria.
Protein
A complex biological molecule composed of a chain of units called amino acids. Proteins have many different functions: structure(collagen); movement (actin and myosin); catalysis (enzymes); transport (hemoglobin); regulation of cellular processes (insulin); and response to the stimuli (receptor proteins on surface of all cells).The information for making proteins is stored in the sequence of nucleotides in the DNA molecule.
Protein engineering
A technique used in the production of proteins with new or artificial amino acid sequences.
Protoplast
A plant or bacterial cell that has had its cell wall removed.
Recombinant DNA
DNA that is formed through combining DNA from two different sources. Humans direct the formation of recombinant DNA through selective breeding and genetic engineering.
Recombinant DNA (rDNA) technology
The laboratory manipulation of DNA in which DNA, or fragments of DNA from different sources, are cut and recombined using enzymes. This recombinant DNA is then inserted into a living organism. rDNA technology is usually used synonymously with genetic engineering.
Recombination
The formation of new combinations of genes. Recombination occurs naturally in plants and animals during the production of sex cells (sperm, eggs, pollen) and their subsequent joining in fertilization. In microbes, genetic material is recombined naturally during conjugation.
Regeneration
The process of growing an entire plant from a single cell or group of cells.
Restriction enzymes
Bacterial enzymes that cleave DNA at very specific locations.
Restriction map
A diagram that shows restriction sites (i.e., where a restriction enzyme cleaves DNA) in relation to one another.
RNA (Ribonucleic acid)
Like DNA, a type of nucleic acid. There are three major types: messenger RNA, transfer RNA, and ribosomal RNA. All are involved in the synthesis of proteins from the information contained in the DNA molecule.
Short Interfering RNA (siRNA)
Also known as small interfering RNA or silencing RNA, is a man-made particle created from a class of biochemical molecules called nucleic acids. Nucleac acids, also components of DNA, are the basic genetic material found in the cells of all living creatures. Scientists are developing ways to use siRNAs as molecular "switches" to temporarily silence, or stop genes from functioning normally. That lets researchers study genes' function more clearly -- and may become a new form of gene therapy for disease treatment. Docking the right piece of siRNA onto a specific "sweet spot" of a gene in a cancerous tumor, for example, could silence the gene so it couldn't send out its usual signals attracting blood vessels to the tumor. So the tumor would starve and the cancer would disappear.
Tissue culture
A procedure for growing or cloning enough cells through in vitro techniques to make a tissue.
Tlymphocytes (T cells)
White blood cells, produced in the bone marrow, that aid B cells in making antibodies to fight bacterial infections. They also are instrumental in rejection of foreign tissue, and may be important in the body's defense against cancer.
Transformation
A change in the genetic structure of an organism as a result of the uptake and incorporation of foreign DNA.
Transposon
A mobile genetic element that can move from one location in the gene and reinsert at another site.
Vector
The agent used to carry new DNA into a cell. Viruses or plasmids are often used as vectors.
Virus
An infectious agent composed of a single type of nucleic acid, DNA or RNA, enclosed in a coat of protein. Viruses can multiply only within living cells.